Copper(I) halide complexes of the new 4,4′-bridged heteroaromatic biscarbenes of the 1,2,4-triazole series

Tandem transformations of 1,2,4-triazol-5-ylidenes into 5-amidino-1,2,4-triazoles

“…Subsequently, Arduengo and co-workers have shown that 4,5-dihydroimidazol-2-ylidenes (but not 1,3-diadamantylimidazol-2-ylidene) undergo C-H insertion reactions with acetonitrile. 19 The reaction of the 4,4′-bridged bistriazol-5-ylidene with diphenyldiazomethane in toluene solution (in which it is only slightly soluble) proceeds at 50 °C for 10 h. 20 The formation of the related azines from imidazol-2-ylidenes has also been described.…”

A base induced transformation of a 1,3-dimethyl-1,3-di(1-adamantyl)formamidinium salt into β-[methyl-(1-adamantyl)amino]acrylonitriles in aliphatic nitriles

“…It is interesting to note that the range of chemical shift changes for the meso-protons of aromatic 1,2,4-triazolium salts are significantly larger, the average values being typically ∆δ = 1.7 -1.8 ppm. 18 The foregoing observations imply that there is only modest electronic communication between the amino moiety and the meso-carbon atom in the case of amidines and their salts.…”

Synthesis of heteroaromatic 3,3′-bridged biscarbenes of the 1,2,4-triazole series and their properties

“…To analyze the structure we used not only the metrical parameters of the molecule (bond lengths and angles) but also the bond orders calculated using the linear dependence of bond lengths and bond orders (p) in model compounds (ethane С-С, 1.534 А; ethylene C=C, 1.337 А; methylamine С-N, 1.474 А; methylenimine С=N, 1.300 А; hydrazine N-N, 1.449 А and azomethane N=N, 1.254 А) (Figure 1, Table 1) in a similar fashion to that described previously. 6 For comparison of the X-ray data one mononuclear carbene 1-tert-butyl-3-phenyl-4-(4-bromophenyl)-1,2,4-triazol-5-ylidene А was also used, as described in reference 17. The molecular structure of 5d features an overall trans conformation and the phenylene link is twisted by 30° with respect to the triazole rings.…”

“…Recently, we have reported the syntheses of 4,4'-bridged bis-1,2,4-triazol-5-ylidenes with conjugated structures. 6 In the present contribution we describe (i) the synthesis of four 3,3′-bridged bis-1,2,4-triazol-5-ylidenes 5a-d, including those with conjugated structures, 5a,b,d; (ii) the preparation of the copper (I) carbene complexe 8 supported by the 1,3-bis-(1-adamantyl-4-phenyl-1,2,4-triazol-5-yliden-3-yl)benzene ligand 5b, (iii) adducts of the biscarbene 5d with sulfur (6) and diphenyldiazomethane (7); (iv) the single crystal X-ray structure of 1,4-bis-(1-tert-butyl-4-phenyl-1,2,4-triazol-5-yliden-3-yl)benzene 5d and (v) the complex of 1,3-bis-(1-adamantyl-4-phenyl-1,2,4-triazol-5-yliden-3-yl)benzene with copper (I) chloride (8).…”